Originally Posted by christsaves
if it were me i would just go ahead and replace both needle and seat valves .. it really is no big deal to replace and adjust them.. you dont have to tare into the carb to replace them.. they are right on top of the carb.. one on the front bowl and one on the back.. all you should need to do the job is a 5/8 wrench and a flat head screwdriver (the bigger the screwdriver the better).. use the screwdriver to break them loose then you should be able to just screw them out by hand.. once they are out it will be up to you as to wether you want or need to change the gaskets.. then just put the new ones in..start the engine and set the needle and seat.. there are two brass screws that should be on the right side of the carb.. one on front bowl and one on back.. pull them out....you use the 5/8 to adjust the float level and the screwdriver to lock down.. turn to the right to take the level down and to the left to bring it up.. the two brass screws is where you check the level.. if gas is steady coming out of the hole the level is too high.. if you can rock the boat and no gas at all is coming out the level is too low.. you should be able to give the boat a little shake and see gas come out.. you want the gas level to be right at the bottom of the hole where you removed the brass screws..
With a 4160 of this vintage there is a pretty good chance the needle and seat is not accessible from outside of the carb and it will be required to take the fuel bowls off. If this is the case, the floats must also be set dry with the bowl separated from the carb.
Has the carb been rebuild recently? If not, you will probably destroy the seals taking the carb apart and it only takes purchasing a few parts before you should just spend the $25 on a rebuild kit (you can order it from you local parts store, should be the 703-29 but you should contact holley and verify by the list # stamped on your carb).
If you have rebuilt it recently, then you should have the new seals that tend not to stick and the needle and seat are probably the newer style with the rubber tip which should clean up well. In that case, just disassemble, clean, set the float, put back together. That is really all there is to it.
<edit> there is also a chance your float has a leak in it and will need to be replaced. Check that out while you have it apart <\edit>